Background: High-risk early triple-negative breast cancer (TNBC) is frequently associated with early recurrence and high mortality. Studies suggest a sustained clinical benefit in patients with TNBC who have a pathological complete response (PCR) after neoadjuvant chemotherapy (NACT). In TNBC, the combination of cancer immunotherapy based on PD-1/PD-L1 immune checkpoint inhibitors with chemotherapy was effective both in advanced and early setting phase 3 clinical trials, in this last scenario the addition of pembrolizumab to platinum containing NACT resulted in a significant increase of pathological complete response. Methods: We performed a retrospective observational cohort study of patients with early TNBC, stage I-III who received neoadjuvant treatment with chemotherapy based on doxorubicin, cyclophosphamide, paclitaxel and carboplatin associated with pembrolizumab treaties from January 2022 to January 2023, in AC Camargo Cancer Center, São Paulo, Brazil, to evaluate their clinical-pathological characteristics. Results: All 52 patients were women, 60,4% premenopausal, with a median age of 42 years old when diagnosed, 59.6% had comorbidities, most commonly hypertension, and 1.9% had an autoimmune disease. About 16.7% germline mutation in the BRCA 1 and 8.3% in the BRCA 2 gene. Regarding pathological characteristics of the tumor, 98% were invasive ductal carcinoma, 78% with histological grade III, 89.8% had nuclear grade III, 51.1% with score 3 mitoses. There were 56,3% with weak, 35,4% with moderate, and 8,3% with intense Tumor Infiltrating Lymphocytes Stromal (TILS). In 47.1% of cases, the ki67 was greater than 80%. The expression of HER 2 was low in 23,8%. About the clinical stage of the tumor 65.4% were cT2 and 17.3% cT3, being cN0, cN1 and cN2a was 40.4%, 36.5% and 13.5%, respectively and grouped clinical stage 40.45 IIA, 25% IIB and 19.2% IIIA. Treatment-related toxicities 20% patients had immune related toxicities, being the main one 30% endocrinologic and 20% hepatic, being that 36.4% occurring after the second cycle. Due to the toxicities, 22.2% of the patients had their treatment delayed. In terms of treatment, 68.6% had begun with platinum and taxane, and 7.8% received dense dose AC (ACdd). Now, only 42.6% of the patients have completed all NACT and 53.2% are still on treatment. From these, 56.8% had complete clinical response, 2.3% stable disease and and those who have already finished and operated 66.7% complete pathological response. Conclusions: Our cohort is mostly pre-menopausal cT2, cN0, stage IIA. Twenty percent of them had IRT, the most common being endocrine and hepatic, which occurred early after the second cycle, leading to treatment delay in 22.2%. About 8% received ACdd, of the patients who completed the treatment and underwent surgery, 66.7% had a complete pathological response.